New Syntax or a glitch?

Hi Nozama ,

Thanks for reaching out to the Microsoft fabric community forum.

You're on the right track when a table name contains special characters like square brackets [], DAX requires it to be wrapped in single quotes.

Try using this :
Measure1 = CALCULATE([Measure2], ALL('ABCDEF [Master]'))

This tells DAX to interpret the entire string as a single table name, avoiding syntax errors.

If the response has addressed your query, please Accept it as a solution and give a 'Kudos' so other members can easily find it

Best Regards,
Tejaswi.
Community Support Team